Photoflash lamp, method of making same, and photoflash circuit

Abstract

An electrically-activated photoflash lamp which includes a glass envelope, combustion-supporting (e.g. oxygen) atmosphere, a quantity of filamentary combustible material (e.g. zirconium), and an ignition means including a pair of spaced leads sealed within the envelope and a primer mass for igniting the combustible material. The primer mass includes a first quantity of substantially non-ignitable primer material having a second quantity of highly ignitable primer material located thereon. Use of the first primer material permits pulsing of the lamp in air prior to application of the second primer material to thereby assure uniform ignition voltages between lamps similarly treated. A circuit utilizing a plurality of the above lamps and a method for producing said lamps are also disclosed.

We claim: 
     
       1. In a photoflash lamp including a hermetically-sealed, light-transmitting envelope having a combustion-supporting atmosphere and a quantity of filamentary combustible material therein, and an ignition means for igniting said combustible material including a pair of spaced electrical conductors and a primer mass, each of said conductors sealed within said envelope and projecting therefrom and having an end portion having access to the interior of said envelope, the improvement wherein said primer mass comprises: a first quantity of pulsed, substantially non-ignitable primer material positioned in electrical contact with both of said end portions of said electrical conductors; and   a second quantity of readily ignitable primer material located in physical contact with at least a portion of said first quantity of primer material.   
     
     
       2. The improvement according to claim 1 further including an electrically insulative member located within said envelope, said end portions of said electrical conductors secured therein and said first quantity of primer material located thereon. 
     
     
       3. The improvement according to claim 2 wherein said insulative component comprises a glass bead. 
     
     
       4. The improvement according to claim 1 wherein said first quantity of primer material is substantially free of an oxidizing agent. 
     
     
       5. The improvement according to claim 4 wherein said first quantity of primer material includes a combustible, particulate fuel and a binding agent, said combustible fuel comprising from about 85 to about 95 percent by weight of said first quantity, said binding agent comprising from about 1 to about 5 percent by weight of said first quantity. 
     
     
       6. The improvement according to claim 5 wherein said first quantity of primer material further includes an additive of finely divided inert, nonconductive material, said inert material comprising from about 1 to about 7 percent by weight of said first quantity. 
     
     
       7. The improvement according to claim 6 wherein said combustible fuel is zirconium, said binding agent is nitrocellulose, and said inert material is fumed alumina. 
     
     
       8. The improvement according to claim 4 wherein said second quantity of primer material comprises a combustible particulate fuel, an oxidizing agent, and a binding agent, said fuel comprising from about 50 to about 85 percent by weight of said second quantity, said oxidizing agent comprising from about 15 to about 50 percent by weight of said second quantity, and said binding agent comprising from about 1 to 4 percent by weight of said second quantity. 
     
     
       9. The improvement according to claim 8 wherein said second quantity of primer material further includes an additive of finely divided, inert nonconductive material, said inert material comprising from about 1 to about 7 percent by weight of said second quantity. 
     
     
       10. The improvement according to claim 9 wherein said combustible fuel is zirconium, said oxidizing agent is potassium perchlorate, said binding agent is nitrocellulose, and said inert material is fumed alumina. 
     
     
       11. A method of making a photoflash lamp, said method comprising: providing a tubular, light-transmitting member having first and second open ends;   positioning a pair of spaced-apart electrical conductors within a first of said open ends;   hermetically sealing said first open end to include said conductors therein such that each of said conductors project therefrom and include an end portion having access to the interior of said tubular member;   positioning a first quantity of substantially non-ignitable primer material in electrical contact with said end portions of said conductors through said second open end;   applying a voltage across said electrical conductors to subject said first quantity of primer material to an electrical breakdown, and thereafter positioning a second quantity of readily ignitable primer material in physical contact with at least a portion of said first quantity of primer material through said second open end;   positioning a quantity of filamentary combustible material within said tubular, light-transmitting member through said second open end;   introducing a combustion-supporting atmosphere within said tubular, light-transmitting member through said second open end; and   sealing said second end to define a hermetically-sealed envelope.   
     
     
       12. The method according to claim 11 wherein said first quantity of primer material is subjected to said electrical breakdown in air. 
     
     
       13. The method according to claim 11 wherein said first quantity of primer material is positioned in contact with said conductors in slurry form and thereafter dried prior to said electrical breakdown. 
     
     
       14. The method according to claim 13 wherein said first quantity of primer material is dried using forced hot air. 
     
     
       15. The method according to claim 11 wherein said second quantity of primer material is positioned in physical contact with said first quantity of primer material in slurry form and thereafter dried. 
     
     
       16. The method according to claim 15 wherein said second quantity of primer material is dried using forced hot air. 
     
     
       17. The method according to claim 11 further including securing end portions of said electrical conductors within an electrically insulative member prior to positioning said conductors within said first open end of said light-transmitting member. 
     
     
       18. A photoflash circuit comprising: at least two photoflash lamps electrically joined in a parallel arrangement for being sequentially flashed by sequential firing voltage pulses, said parallel arrangement adapted for being connected across a source of said firing voltage pulses, each of said photoflash lamps including a hermetically-sealed, light-transmitting envelope having a combustion-supporting atmosphere and a quantity of filamentary combustible material therein and an ignition means for igniting said combustible material including a primer mass and a pair of spaced electrical conductors sealed within said envelope and projecting therefrom and having an end portion having access to the interior of said envelope, said primer mass including a first quantity of pulsed, substantially non-ignitable primer material positioned in electrical contact with both of said end portions of said conductors and a second quantity of readily ignitable primer material located in physical contact with at least a portion of said first quantity of primer material, each of said photoflash lamps having substantially similar ignition voltages; and   at least one arc gap member connected in electrical series with one of said photoflash lamps.   
     
     
       19. The photoflash circuit according to claim 18 wherein said arc gap member comprises a pair of conductive elements spaced apart a predetermined distance, said conductive elements positioned on an electrically insulative substrate. 
     
     
       20. The photoflash circuit according to claim 19 wherein said arc gap member further comprises an insulative member located atop and interconnecting each of said conductive elements, and a conductive path positioned atop said insulative member and including a first and second end portions respectively located a preestablished distance from one of said conductive elements. 
     
     
       21. The photoflash circuit according to claim 19 wherein said arc gap member further comprises an insulative member located atop and interconnecting each of said conductive elements and a conductive path positioned atop said insulative member and including first and second end portions, said first end portion located a preestablished distance from a first of said conductive elements, said second end portion positioned in electrical contact with a second of said conductive elements. 
     
     
       22. The photoflash circuit according to claim 18 wherein the number of said photoflash lamps is at least three and the number of arc gap members is at least two, said arc gap members respectively connected in electrical series with a similar number of said photoflash lamps thereby forming a plurality of series arrangements connected in parallel, each of said arc gap members having different voltage breakdown values each less than the voltage of said firing voltage pulses.